1 UNIT 4 the ORIGIN and the END of the UNIVERSE Contents 4.0 Objectives 4.1 Introduction 4.2 the Origin of the Universe 4

1 UNIT 4 THE ORIGIN AND THE END OF THE UNIVERSE Contents 4.0 Objectives 4.1 Introduction 4.2 The Origin of the Universe 4.3 The End of the Universe 4.4 Let Us Sum Up 4.5 Key Words 4.6 Further Readings and References 4.0 OBJECTIVES • To familiarise ourselves with some general theories on the origin and end of the physical universe. • To know that scientific theories on the universe keep on evolving and changing. • To be familiar with the commonly accepted theory on the origin and end of the universe (Big Bang and Big Crunch) 4.1 INTRODUCTION According to Stephen Hawking (1988) the problem of the origin of the universe, is a bit like the old question: Which came first, the chicken, or the egg. In other words, Who created the universe? Or perhaps, the universe, or the agency that created it, existed forever, and didn't need to be created. Up to recently, scientists have tended to shy away from such questions, feeling that they belonged to metaphysics or religion, rather than to science. However, in the last few years, it has emerged that the Laws of Science may hold even at the beginning of the universe and also may explain the end of the universe. The debate about whether, and how, the universe began, has been going on throughout recorded history. Basically, there were two schools of thought. Many early traditions, and the Jewish, Christian and Islamic religions, held that the universe was created in the fairly recent past. For instance, Bishop Usher calculated a date of four thousand and four BC, for the creation of the universe, by adding up the ages of people in the Old Testament. One fact that was used to support the idea of a recent origin, was that the Human race is obviously evolving in culture and technology. We remember who first performed that deed, or developed this technique. Thus, the argument runs, we cannot have been around all that long. Otherwise, we would have already progressed more than we have. In fact, the biblical date for the creation, is not that far off the date of the end of the last Ice Age, which is when modern humans seem first to have appeared. The universe of 100 years ago was simple: eternal, unchanging, consisting of a single galaxy, containing a few million visible stars. The picture today is more complete and much richer. The cosmos began 13.7 billion years ago with the big bang. A fraction of a second after the 2 beginning, the universe was a hot, formless soup of the most elementary particles, quarks and leptons. As it expanded and cooled, layer on layer of structure developed: neutrons and protons, atomic nuclei, atoms, stars, galaxies, clusters of galaxies, and finally superclusters. The observable part of the universe is now inhabited by 100 billion galaxies, each containing 100 billion stars and probably a similar number of planets. Galaxies themselves are held together by the gravity of the mysterious dark matter. The universe continues to expand and indeed does so at an accelerating pace, driven by dark energy, an even more mysterious form of energy whose gravitational force repels rather than attracts. In this context, this unit attempts to give some of the common theories on the origin and end of the universe from scientific perspectives. The religious perspectives are not considered here. 4.2 THE ORIGIN OF THE UNIVERSE Some of the common scientific theories explaining the beginning of the universe Steady State Theory Steady State Theory proposes that matter is being continuously created, at the rate of a few hundred atoms per year. This would allow the density of the universe to remain constant as it expands. It holds that the universe looks, on the whole, the same at all times and places. The Austrian-British astronomer Hermann Bondi and the Austrian-American astronomer Thomas Gold formulated the theory in 1948. The British astronomer Fred Hoyle soon published a different version of the theory based on his mathematical understanding of the problem. Most astronomers believe that astronomical observations contradict the predictions of the steady-state theory and uphold the big bang theory. The infinite duration of time was the most appealing feature of the steady state theory. Even the notion of creation was used to advantage: the failure to detect a large flux of gamma rays led to the proposal that creation preferentially took place only in dense galactic nuclei and quasars. This proposal initially met with some enthusiasm, because it appeared to solve two problems: continuous creation was revived, and an ample energy source was provided for the most energetic objects in the universe. However, three shortcomings eventually led to the demise of steady state cosmology. First, astronomers have discovered a large increase in the number of faint radio sources as the limiting flux level is systematically decreased. The number that they estimate is well above that expected for a uniform source distribution in Euclidean space, which suggests that strong evolutionary effects are occurring at great distances. The notion of an excess number of distant faint sources did not find universal acceptance. For several years, Hoyle was able to argue that an equally plausible hypothesis was a deficit of nearby bright sources. Now, however, it seems clear with measured redshifts that the highly red shifted sources, most notably the radio galaxies and the quasars, reveal strong evolutionary effects. Equal volumes of space contain progressively more quasars and powerful radio galaxies at greater distances. Looking at evidence, explanations, rationalizations, and arguments for naturalistic origins of the universe leads to a simple conclusion. Once all of the cards are on the table, recent discoveries have given life to interpretations that are long on theory and short on proof. To put it another way, all scientists have really proven about the origin of the universe is that they don’t really know how it happened, and they may be looking at it the wrong way. 3 Check Your Progress I Note: Use the space provided for your answer 1) Give an approximate size of our universe? ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 2) Give a brief description of the steady-state theory. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… Big Bang Theory The Big Bang theory is an effort to explain what happened at the very beginning of our universe. Discoveries in astronomy and physics have shown beyond a reasonable doubt that our universe did in fact have a beginning. According to the standard theory, our universe sprang into existence as "singularity" around 13.7 billion years ago. Our universe is thought to have begun as an infinitesimally small, infinitely hot, infinitely dense, something - a singularity. We don't know where it came from not why did it appear. After its initial appearance, it apparently inflated (the "Big Bang"), expanded and cooled, going from very, very small and very, very hot, to the size and temperature of our current universe. It continues to expand and cool to this day and we are inside of it: incredible creatures living on a unique planet, circling a beautiful star clustered together with several hundred billion other stars in a galaxy soaring through the cosmos. Evidence for the Theory First of all, we are reasonably certain that the universe had a beginning. Second, galaxies appear to be moving away from us at speeds proportional to their distance. This is called "Hubble's Law," named after Edwin Hubble (1889-1953) who discovered this phenomenon in 1929. This observation supports the expansion of the universe and suggests that the universe was once compacted. Third, if the universe was initially very, very hot as the Big Bang suggests, we should be able to find some remnant of this heat. In 1965, Radio astronomers Arno Penzias and Robert Wilson discovered a 2.725 degree Kelvin (-454.765 degree Fahrenheit, -270.425 degree Celsius) Cosmic Microwave Background radiation (CMB) which pervades the observable universe. This is thought to be the remnant which scientists were looking for. Penzias and Wilson shared in the 1978 Nobel Prize for Physics for their discovery. Finally, the abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins. Big Bang Theory - What About God? Any discussion of the Big Bang theory would be incomplete without asking the question, what about God? This is because cosmogony (the study of the origin of the universe) is an area where science and theology meet. Creation was a supernatural event. That is, it took place outside of the natural realm. This fact begs the question: is there anything else which exists outside of the natural realm? Specifically, is there a master Architect out there? We know that this universe had a beginning. Was God the "First Cause"? 4 Check Your Progress II Note: Use the space provided for your answer 1) Give a brief description of Big Bang? ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 2) What are some of the evidences for Big Bang Theory. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 4.3 THE END OF THE UNIVERSE Theories explaining the end of the universe are the following. Heat Death German physicist Hermann von Helmholtz made a prediction in the year 1856 that the universe is dying. This prediction was based on the law of thermodynamics. A more thoroughgoing analysis enables this law to be generalized to all closed systems: the entropy never falls. If the universe as a whole can be considered as a closed system, on the basis that there is nothing ‘outside’ it, then the second law of thermodynamics makes an important prediction: the total entropy of the universe never decreases.

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